SUMMARYDuring the lifetime of an angiosperm plant various important processes such as floral transition, specification of floral organ identity and floral determinacy, are controlled by members of the MADS domain transcription factor family. To investigate the possible non-cell-autonomous function of MADS domain proteins, we expressed GFP-tagged clones of AGAMOUS (AG), APETALA3 (AP3), PISTILLATA (PI) and SEPALLATA3 (SEP3) under the control of the MERISTEMLAYER1 promoter in Arabidopsis thaliana plants. Morphological analyses revealed that epidermal overexpression was sufficient for homeotic changes in floral organs, but that it did not result in early flowering or terminal flower phenotypes that are associated with constitutive overexpression of these proteins. Localisations of the tagged proteins in these plants were analysed with confocal laser scanning microscopy in leaf tissue, inflorescence meristems and floral meristems. We demonstrated that only AG is able to move via secondary plasmodesmata from the epidermal cell layer to the subepidermal cell layer in the floral meristem and to a lesser extent in the inflorescence meristem. To study the homeotic effects in more detail, the capacity of trafficking AG to complement the ag mutant phenotype was compared with the capacity of the non-inwards-moving AP3 protein to complement the ap3 mutant phenotype. While epidermal expression of AG gave full complementation, AP3 appeared not to be able to drive all homeotic functions from the epidermis, perhaps reflecting the difference in mobility of these proteins.

Most of the plant pigments ranging from red to purple colors belong to the anthocyanin group of flavonoids. The flowers of plants belonging to the genus Passiflora (passionflowers) show a wide range of floral adaptations to diverse pollinating agents, including variation in the pigmentation of floral parts ranging from white to red and purple colors. Exploring a database of expressed sequence tags obtained from flower buds of two divergent Passiflora species, we obtained assembled sequences potentially corresponding to 15 different genes of the anthocyanin biosynthesis pathway in these species. The obtained sequences code for putative enzymes are involved in the production of flavonoid precursors, as well as those involved in the formation of particular (“decorated”) anthocyanin molecules. We also obtained sequences encoding regulatory factors that control the expression of structural genes and regulate the spatial and temporal accumulation of pigments. The identification of some of the putative Passiflora anthocyanin biosynthesis pathway genes provides novel resources for research on secondary metabolism in passionflowers, especially on the elucidation of the processes involved in floral pigmentation, which will allow future studies on the role of pigmentation in pollinator preferences in a molecular level.

No abstract

Changes in flower morphology may influence the frequency and specificity of animal visitors. In Petunia (Solanaceae), adaptation to different pollinators is one of the factors leading to species diversification within the genus. This study provides evidence that differential expression patterns of MAWEWEST (MAW) homologs in different Petunia species may be associated with adaptive changes in floral morphology. The Petunia × hybrida MAW gene belongs to the WOX (WUSCHEL-related homeobox) transcription factor family and has been identified as a controller of petal fusion during corolla formation. We analyzed the expression patterns of P. inflata and P. axillaris MAW orthologs (PiMAW and PaMAW, respectively) by reverse transcriptase polymerase chain reaction (RT-PCR), reverse transcription–quantitative PCR (qRT-PCR) and in situ hybridization in different tissues and different developmental stages of flowers in both species. The spatial expression patterns of PiMAW and PaMAW were similar in P. inflata and P. axillaris. Nevertheless, PaMAW expression level in P. axillaris was higher during the late bud development stage as compared to PiMAW in P. inflata. This work represents an expansion of petunia developmental research to wild accessions.

No abstract

No abstract

No abstract

No abstract